lnu.sePublications
Change search
Refine search result
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Allen, Peter M.
    et al.
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Radhakrishnan, Hema
    Vision Cooperative Research Centre, Australia ; University of Manchester, UK.
    Price, Holly
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Rae, Sheila
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Theagarayan, Baskar
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Calver, Richard I.
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Sailoganathan, Ananth
    National Institute of Ophthalmic Sciences, Malaysia.
    Latham, Keziah
    Anglia Ruskin University, UK.
    O'Leary, Daniel J.
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    A randomised clinical trial to assess the effect of a dual treatment on myopia progression: the Cambridge anti-myopia study2013In: Ophthalmic & physiological optics, ISSN 0275-5408, E-ISSN 1475-1313, Vol. 33, no 3, p. 267-276Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To evaluate the effect of a dual treatment modality for myopia, by improving accommodative functions, on myopia progression.

    METHODS: A double blind randomised control trial was conducted on 96 subjects. The treatment modality for the trial employed custom designed contact lenses which control spherical aberration in an attempt to optimise static accommodation responses during near-work, and a vision-training programme to improve accommodation dynamics. Myopia progression was assessed over a 2 year period using cycloplegic autorefraction and biometry.

    RESULTS: The mean progression was found to be -0.33 Dioptres (D) over the 2 years of the study. There was no interaction between contact lens treatment and vision training treatment at 24 months (p = 0.72). There was no significant treatment effect of either Vision Training or Contact Lens Spherical Aberration control on myopia progression.

    CONCLUSIONS: This study is unable to demonstrate that the progression of myopia can be reduced over a 2 year period by either of the two treatments aimed at improving accommodative function. Neither treatment group (contact lens or vision training) progressed at a slower rate over the 2 years of the study than did the appropriate control group.

  • 2.
    Allen, Peter M.
    et al.
    Anglia Ruskin University, UK.
    Radhakrishnan, Hema
    University of Manchester, UK.
    Rae, Sheila
    Anglia Ruskin University, UK.
    Calver, Richard I.
    Anglia Ruskin University, UK.
    Theagarayan, Baskar
    Anglia Ruskin University, UK.
    Nelson, Paul
    Prism Training Consultancy, UK.
    Osuobeni, Ebi
    Anglia Ruskin University, UK.
    Sailoganathan, Ananth
    Anglia Ruskin University, UK.
    Price, Holly
    Anglia Ruskin University, UK.
    O'Leary, Daniel J.
    Anglia Ruskin University, UK.
    Aberration control and vision training as an effective means of improving accommodation in individuals with myopia.2009In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 50, no 11, p. 5120-5129Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To test the efficacy of a novel dual treatment for improving accommodative accuracy and dynamics in young persons with myopia.

    METHODS: Ninety-three young persons with myopia (mean spherical equivalent, -3.0 +/- 1.8 D; age 16.8 +/- 2.1 years; spherical aberration +0.06 +/- 0.04 microm) participated in the study. Custom-designed soft contact lenses were used to alter ocular SA to -0.10 microm to improve accommodative accuracy and reduce any lag of accommodation. A vision training regimen was performed for 18 minutes per day for up to 6 weeks to improve speed of dynamic accommodation. Control groups had contact lenses with no added SA and/or no exercises. To avoid any effects of natural levels of negative aberration on the results of the study, all participants who had negative SA were excluded.

    RESULTS: The treatment contact lenses produced a significant reduction in lag of accommodation (P < 0.05) at all proximal viewing distances measured. The vision training measurement and treatment resulted in a significant increase in distance facility rate for all groups compared with their own baselines (P < 0.05). Near facility rate improved in the vision training treatment group only compared with its baseline (P < 0.05). Both positive and negative response times for distant viewing were significantly shorter in all groups after training compared with their baseline values (P < 0.05). At near, the positive response times were decreased significantly (P < 0.05) in both groups, whereas the negative response times decreased significantly only in the vision training treatment group.

    CONCLUSIONS: After 3 months, the dual treatments (altering SA and vision training) used in the study were effective in modifying accommodation. The static accommodative response to targets at proximal distances was increased by the altered SA contact lenses and rates of dynamic accommodation improved with vision training.

  • 3.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Olsson, Roger
    Theagarayan, Baskar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Effect of accommodation on peripheral refraction in myopes and emmetropes using a COAS-HD VR open field aberrometer.2016Conference paper (Refereed)
    Abstract [en]

    Purpose To investigate the effect of accommodation on both central and peripheral refractive errors in myopes compared to emmetropes using a COAS-HD VR open field aberrometer. Methods 15 myopic subjects (-1.50 D to -8.25 D) and 14 emmetropic subjects (+0.75 D to -0.25 D) participated in this study. The mean age of the myopic group was 24.3 ± 5.7 years and for the emmetropic group was 23.9 ± 5.7 years. Central and peripheral refraction were measured with a COAS-HD VR open field instrument at seven different eccentricities from 0° to ± 30° in 10° steps for three different accommodative demands 0.33 D, 2.50 D and 4.0 D during monocular viewing. The myopic subjects were corrected with soft contact lenses and the measurements were performed on the right eye for a 3 mm pupil diameter for both groups. Relative peripheral refractive error (RPRE) was calculated for all three accommodative demands for both groups. Results Repeated measures ANOVA showed no significant difference in RPRE across eccentricities or between accommodation demands in the myopes (pÂż0.05). The myopic group had minimal hyperopic shift in the periphery for all three accommodative demands. The largest mean hyperopic shift was 0.37 D at 30° nasal retina for an accommodative demand of 4.0 D. On the other hand, the emmetropic group became relatively myopic at peripheral eccentricities, from 20° onwards for all three accommodative demands. The largest mean myopic shift was 1.01 D at 30° temporal retina for an accommodative demand of 2.50 D. Conclusion In the myopic group, we did not find any significant reduction in hyperopic shift in the periphery with accommodation. The emmetropic group showed myopic shift in the periphery for all three accommodative demands with temporal retina being more myopic than nasal retina.

  • 4.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Carius, Staffan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Influence of age on peripheral aberration2010Conference paper (Refereed)
    Abstract [en]

    The purpose of this study is to compare peripheral higher order aberrations in young

    and old emmetropic eyes across the horizontal (±40°) and inferior (–20°) visual field.

    Introduction

     

     

    People with central visual field loss use eccentric fixation for various visual tasks.

    Recently studies have shown that the correction of lower order aberrations (defocus &

    astigmatism) can improve eccentric vision in subjects with central visual field loss

    (CFL)[1]. The CFL subjects mostly correspond to older age groups who use eccentric

    fixation angles up to 20°–30°. While there have been studies comparing the off-axis

    lower order aberrations in normal young and old subjects[2], there is only one recent

    study, which has compared off-axis higher order aberrations in normal young and old

    emmetropic eyes up to 20° (horizontal and vertical) eccentricity[3]. In this study we

    have measured off-axis aberrations in a group of 10 young (23 ± 3 years) and 10 old

    (57 ± 4 years) emmetropes. The aberrations of the right eye were measured using

    COAS-HD VR Hartmann-Shack aberrometer in steps 10° out to ± 40° horizontally and

    –20° inferiorly in the visual field. Subjects rotated the eyes to view the fixation targets,

    which were red light emitting diodes, placed at 3 meter from the eye. The aberrations

    were quantified for a pupil area 5 mm in diameter.

    Discussion

     

     

    Mixed between-within subject’s analysis of variance of the horizontal coma C13

    showed that there was a statistically significant difference between age groups

    (p<0.05). The coma increased linearly in both groups from nasal to temporal visual

    field. The rate of change was greater in the old (slope = –0.027 μm/deg) compared

    to the young (slope = –0.012 μm/deg) emmetropes. In the inferior visual field,

    vertical coma C-13 changed linearly in both groups with higher values in old (slope =

    0.015 μm/deg) compared to young (slope = 0.006 μm/deg). The mean spherical

    aberration was positive in older emmetropes (0.053 μm) compared to young

    emmetropes (-0.030 μm). The HO RMS showed a quadratic increase in the

    periphery for both age groups. The HO RMS was greater in older emmetropes but it

    was not statistically significant (p>0.05) when compared to young emmetropes.

     

    Conclusions

     

     

    Our results show that there is an increase in coma, spherical aberration, and HO

    RMS with age in the periphery.

  • 5.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Carius, Staffan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Measurement of Off-axis Refraction with a Commercial Open Field Aberrometer2010Conference paper (Refereed)
    Abstract [en]

    Purpose:

    People with central visual field loss (CFL) use their remaining peripheral vision in order to see better when performing various visual related tasks. At large off-axis angles, the eccentric vision can be limited both by the low resolution capacity of the peripheral retina and by the optical aberrations caused due to oblique angles. Previous work has shown that eccentric correction of induced off-axis astigmatism can improve vision in a preferred retinal location (PRL) for people with CFL. However, the eccentric refraction is often difficult to determine with traditional refractive methods. This work therefore shows the use of a commercially available wavefront sensor to measure fast and reliable off-axis refraction. Data on off-axis refraction is also of interest in the field of myopia research.

    Methods:

    We used the new open-field high-definition complete ophthalmic analysis system, COAS HD -VR, to evaluate off-axis refraction. Using the special Vision Research tool in this system stimulus (fixation objects) can be presented in a large part of the visual field. The instrument can measure out to 40 degrees in the horizontal visual field and 20 degrees in the vertical visual field with a range from sphere +7 D to − 17 D. It measures astigmatism up to 10 D. This instrument also allows natural binocular viewing without obstacles. Aberrations of the right eye of 30 emmetropes (24 ± 4 years) were studied. Off-axis refraction and higher order (HO) aberrations were measured in steps of 10° out to ± 30° in the horizontal visual field

    Results:

    The first data on young emmetropic eyes with this new instrument showed promising results for low (LO) and higher order (HO) aberrations in the peripheral visual field. Of the LO aberrations, astigmatism increased significantly with the off–axis angle, from 0.25 D at 10° Nasal to 1.65 D at 30° Nasal. In the HO aberrations, coma (C13) showed a linear increase across the horizontal visual field (p < 0.05)

    Conclusions:

    The COAS HD-VR shows promising results and good usability for future research in evaluation of off-axis refraction. In future we believe the aberrometer can be used clinically to measure off-axis refractions in low vision patients.

  • 6.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Carius, Staffan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ocular Aberrations in the Peripheral Visual Field With a Commercial Open-View Aberrometer2010In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 51, no 5, article id 3951Article in journal (Refereed)
    Abstract [en]

    PurposeThe interest in off-axis aberrations has increased with the discovery of a possible link between myopia development and peripheral optics. The most common technology to measure the off-axis aberrations is a Shack-Hartmann wavefront aberrometer. This is the first study to report peripheral aberrations in a large sample of emmetropic population with a commercial open-view Shack-Hartmann aberrometer. MethodsThe commercial open-view Shack-Hartmann aberrometer COAS-HD VR was used to measure the aberrations in the peripheral vision. Aberrations of the right eye of 30 emmetropes (24 {+/-} 4 years) were studied. Off-axis aberrations were measured in steps of 10{degrees} out to {+/-} 30{degrees} in the horizontal visual field. The subjects turned their eye to view the off-axis fixation target (light emitting diode placed at 3 meters) during the measurement. The resulting wavefront aberrations were parameterized with Zernike coefficients for a 5 mm diameter pupil. All analyzes are reported according to optical society of America (OSA) recommended standards. ResultsAberrations from the 2nd to 6th order and the total higher-order root-mean-square (HO RMS) were analyzed using one-way ANOVA. The defocus C02 was significantly myopic in the nasal visual field (+20{degrees}, +30{degrees}) whereas there was no significant difference in the temporal visual field. Astigmatism C22 increased quadratically from {+/-}10{degrees} in the periphery and coma C13 showed a linear increase across the horizontal visual field (p < 0.05). The spherical aberration C04 and the total HO RMS showed a significant change at {+/-}30o. ConclusionsOur results showed that in young emmetropes there was a significant increase of HO RMS at {+/-}30{degrees}, which is expected. Astigmatism, horizontal coma, and spherical aberration vary systematically across the horizontal visual field in agreement with Seidel theory. The findings of our study with a large sample of emmetropic population agree with the previous studies done with laboratory built aberrometers.

  • 7.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Carius, Staffan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Repeatability of Peripheral Aberrations in Young Emmetropes2010In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 87, no 10, p. 751-759Article in journal (Refereed)
    Abstract [en]

    PURPOSE.: The purpose of this study is to assess the intrasession repeatability of ocular aberration measurements in the peripheral visual field with a commercially available Shack-Hartmann aberrometer (complete ophthalmic analysis system-high definition-vision research). The higher-order off-axis aberrations data in young healthy emmetropic eyes are also reported.

    METHODS.: The aberrations of the right eye of 18 emmetropes were measured using an aberrometer with an open field of view that allows peripheral measurements. Five repeated measures of ocular aberrations were obtained and assessed in steps of 10 degrees out to +/-40 degrees in the horizontal visual field (nasal + and temporal -) and -20 degrees in the inferior visual field. The coefficient of repeatability, coefficient of variation, and the intraclass correlation coefficient were calculated as a measure of intrasession repeatability.

    RESULTS.: In all eccentric angles, the repeatability of the third- and fourth-order aberrations was better than the fifth and sixth order aberrations. The coefficient of variation was <30% and the intraclass correlation coefficient was >0.90 for the third and fourth order but reduced gradually for higher orders. There was no statistical significant difference in variance of total higher-order root mean square between on- and off-axis measurements (p > 0.05). The aberration data in this group of young emmetropes showed that the horizontal coma (C13) was most positive at 40 degrees in the temporal field, decreasing linearly toward negative values with increasing off-axis angle into the nasal field, whereas all other higher-order aberrations showed little or no change.

    CONCLUSIONS.: The complete ophthalmic analysis system-high definition-vision research provides fast, repeatable, and valid peripheral aberration measurements and can be used efficiently to measure off-axis aberrations in the peripheral visual field

  • 8.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Theagarayan, Baskar
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Low Vision Services System in Scandinavia2009Conference paper (Refereed)
  • 9.
    Henrysson, Ida
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Linnaeus Univ, Dept Med & Optometry, Bergen, Norway..
    Theagarayan, Baskar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Binocular Vision, Reading Ability and Associated Symptoms in School Children2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 7, p. 530-Article in journal (Other academic)
    Abstract [en]

    Purpose: The purpose of this study was to investigate relationship between binocular vision, reading ability and any associated symptoms in School Children.

    Methods: The study was conducted in a School in western Sweden. A sample of 54 Children aged between 10 and 12 years were invited to participate in this study. A consent form and a letter with information was sent to their parents. Children with at least 20/25 and N6 visual acuity and good Stereopsis were included. After receiving consent forms, 27 Children participated in all the measurements. Amplitude of accommodation was measured using push-up method both monocularly and binocularly. Accommodative facility was measured using ± 2.00 D flippers at 40 cm both monocularly and binocularly. Near point of convergence was measured using a Royal Air Force (RAF) ruler and both break and recovery points were documented. All the Children performed a group of reading ability tests to detect whether they have any reading difficulties. A questionnaire called "The College of Optometrists in Vision Development Quality of Life (COVD-QOL)" was filled by their parents together with their Children. A score of 20 or more is considered as symptomatic.

    Results: Mean amplitude of accommodation was OD 10.8 ± 4.0 D, OS 11.8 ± 4.1 D and OU 14.2 ± 3.7 D. Amplitude of accommodation was low in terms of Hofstetter's formula. Based on age, 59% of the Children were below expected value. The accommodative facility was lower than expected, with mean values of OD 5.5 ± 4.0 cpm, OS 5.5 ± 4.0 cpm and OU 5.0 ± 3.5 cpm. Mean near point of convergence was 6.0 ± 5.4 cm for break and 6.6 ± 5.9 cm for recovery. In the reading ability tests all the Children had normal values. Three Children received ≥ 20 points on the symptom questionnaire COVD-QOL, which is considered to be high. All of these three Children had values below normal limits for the amplitude of accommodation and/or the accommodative facility. Regression analysis showed no significant correlation between binocular vision tests, reading ability and symptom score (r < 0.6; p > 0.05).

    Conclusions: Amplitude of accommodation and accommodative facility was lower than expected values for their age. Near point of convergence values reached the expected normal level. There was no significant correlation between binocular vision tests, reading ability and associated symptoms in this sample of Swedish Children.

  • 10.
    Price, Holly
    et al.
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Allen, Peter M.
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Radhakrishnan, Hema
    Vision Cooperative Research Centre, Australia ; University of Manchester, UK.
    Calver, Richard
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Rae, Sheila
    Anglia Ruskin University, UK ; Vision Cooperative Research Centre, Australia.
    Theagarayan, Baskar
    Anglia Ruskin University, UK.
    Sailoganathan, Ananth
    Anglia Ruskin University, UK ; National Institute of Ophthalmic Sciences, Malaysia.
    O'Leary, Daniel J.
    Anglia Ruskin University, UK ; Cardiff Metropolitan University, UK.
    The Cambridge anti-myopia study: variables associated with myopia progression2013In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 90, no 11, p. 1274-1283Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To identify variables associated with myopia progression and to identify any interaction between accommodative function, myopia progression, age, and treatment effect in the Cambridge Anti-Myopia Study.

    METHODS: Contact lenses were used to improve static accommodation by altering ocular spherical aberration, and vision training was performed to improve dynamic accommodation. One hundred forty-two subjects, aged 14-21 years, were recruited who had a minimum of -0.75D of myopia. Subjects were assigned to contact lens treatment only, vision training only, contact lens treatment and vision training, or control group. Spherical aberration, lag of accommodation, accommodative convergence/accommodation (AC/A) ratio, accommodative facility, ocular biometry, and refractive error were measured at regular intervals throughout the 2-year trial.

    RESULTS: Ninety-five subjects completed the 24-month trial period. There was no significant difference in myopia progression between the four treatment groups at 24 months. Age, lag of accommodation, and AC/A ratio were significantly associated with myopia progression. There was a significant treatment effect at 12 months in the contact lens treatment group in younger subjects, based on a median split, aged under 16.9 years (p = 0.005). This treatment effect was not maintained over the second year of the trial. Younger subjects experienced a greater reduction in lag of accommodation with the treatment contact lens at 3 months (p = 0.03), compared to older contact lens treatment and control groups. There was no interaction between AC/A ratio and contact lens treatment effect.

    CONCLUSIONS: Age, lag of accommodation, and AC/A ratio were significantly associated with myopia progression. Although there was no significant treatment effect at 24 months, an interaction between age and contact lens treatment suggests younger subjects may be more amenable, at least in the short term, to alteration of the visual system using optical treatments.

  • 11.
    Radhakrishnan, Hema
    et al.
    University of Manchester, UK ; The Vision Cooperative Research Centre, Australia.
    Allen, Peter M.
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    Calver, Richard I.
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    Theagarayan, Baskar
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    Price, Holly
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    Rae, Sheila
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    Sailoganathan, Ananth
    The Vision Cooperative Research Centre, Australia ; Anglia Ruskin University, UK.
    O'Leary, Daniel J.
    The Vision Cooperative Research Centre, Australia.
    Peripheral refractive changes associated with myopia progression2013In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 54, no 2, p. 1573-1581Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To evaluate the changes in peripheral refraction profiles associated with myopia progression and treatment modalities used in the Cambridge Anti-Myopia Study.

    METHODS: one hundred and seventy-seven myopes in the age range of 14 to 22 years were enrolled in the study. The mean spherical equivalent refractive error was 3.12 1.87 diopters (D) and the refractive error of each participant was corrected with contact lenses. The participants were randomly assigned to one of four treatment groups, which included: altered spherical aberration and vision training, altered spherical aberration only, vision training only, and control. Peripheral refractive error was measured using an open field autorefractor in the central 60° of the retina in 10° steps. The refractive error was measured using cycloplegic autorefraction. Two-year refractive progression data and initial peripheral refraction measurements were available in 113 participants. Measurements of peripheral refraction and cycloplegic refraction were obtained at three visits over 2 years in 12-month intervals for 92 participants.

    RESULTS: All subjects showed a relative peripheral hyperopia, especially in the nasal retina. A limited magnitude of myopia progression of -0.34 ± 0.36 D over 2 years was found in each of the four groups on average. There were no significant differences in the rate of progression between any of the treatment groups (P > 0.05). Initial peripheral J45 astigmatic refractive error at 20° and 30° in the nasal retina was weakly correlated with progression of myopia over 2 years (r = -0.27, P = 0.004 and r = -0.20, P = 0.040, respectively; n = 113). The change in spherical equivalent peripheral refractive error at 30° nasal retina over time was also significantly correlated with progression of myopia especially at 24 months (r = -0.24, P = 0.017, n = 92).

    CONCLUSIONS: Relative peripheral hyperopia is associated with myopia. Myopia progression may be weakly linked to changes in the peripheral refraction profiles in the nasal retina. However, a causative link between peripheral refractive error and myopia progression could not be established.

  • 12.
    Rae, Sheila M.
    et al.
    Anglia Ruskin University, UK.
    Allen, Peter M.
    Anglia Ruskin University, UK.
    Radhakrishnan, Hema
    University of New South Wales, Australia.
    Theagarayan, Baskar
    Anglia Ruskin University, UK.
    Price, Holly C
    Anglia Ruskin University, UK.
    Sailaganathan, Ananth
    Anglia Ruskin University, UK.
    Calver, Richard I.
    Anglia Ruskin University, UK.
    O'Leary, Daniel J
    Anglia Ruskin University, UK.
    Increasing negative spherical aberration with soft contact lenses improves high and low contrast visual acuity in young adults2009In: Ophthalmic & physiological optics, ISSN 0275-5408, E-ISSN 1475-1313, Vol. 29, no 6, p. 593-601Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To evaluate the effects of a customised manipulation of spherical aberration (SA) on the high and low contrast visual acuities and contrast sensitivity of young adult myopes.

    METHODS: A placebo-controlled double masked trial of customised spherical aberration controlling soft contact lenses was undertaken in myopes aged 15-23. Participants wore customised soft contact lenses with either (i) zero spherical aberration or (ii) negative spherical aberration that resulted in a net SA (eye plus lens) of -0.1 micron. High and low contrast log MAR visual acuities and Pelli Robson contrast sensitivity were assessed in 196 eyes of 98 subjects after a period of 12 months wearing the lenses.

    RESULTS: Both high and low contrast acuities were significantly better in the group wearing the contact lenses with negative spherical aberration (high contrast log MAR, p = 0.043; low contrast log MAR, p = 0.043) which was not due to differences in residual astigmatism or pupil size between the two groups. Pelli Robson contrast sensitivity was not significantly different in the two groups.

    CONCLUSIONS: Manipulation of spherical aberration, taking account of the participants' baseline level of aberration, can cause statistically significant improvements in high and low contrast distance visual acuity although these improvements are too small in magnitude to be of clinical significance.

  • 13.
    Theagarayan, Baskar
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    MANIPULATION OF OCULAR ABERRATIONS IN MYOPES2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Myopia is a major cause of vision loss throughout the world. High myopia is associated with severe eye diseases like maculopathy, retinal detachment and glaucoma. The prevalence of myopia is increasing, and varies by country and by ethnic group. In some Asian populations the prevalence is 70%-80%. 

    This thesis includes five experiments. In experiment I we investigated the effects of added positive and negative spherical aberration on accommodative response accuracy. We found that the accommodative response can be altered by modulating the spherical aberration of the eye with soft contact lenses. There was an improvement in the accommodative response slopes and a decrease in the lag of accommodation with the negative spherical aberration lenses compared to positive spherical aberration lenses. 

    In experiment II we investigated whether the negative spherical aberration in contact lenses could be tolerated visually in terms of wearability and comfort. We found that all the subjects were satisfied with the contact lens comfort, distance and near vision and the stability of the vision with the lenses. The accommodative response was stable through out the treatment period.

    In experiment III we investigated the efficacy of a novel dual treatment for the improvement of accommodative accuracy and dynamics in myopes. The spherical aberration of the eye was effectively altered to negative in the treatment group as predicted. In the control group as expected there was no significant change in the spherical aberration of the eye with and without contact lenses. The treatment lenses decreased the lag of accommodation and increased the accommodative response slope at 3 months.

    In the experiment IV we investigated the effect of the treatment lenses used in the previous experiment on high and low contrast visual acuities after a one year treatment period. The results showed a significant improvement in both high and low contrast visual acuities after the one year period in the treatment group compared to the control group, even though it was not clinically significant.

    In experiment V we investigated the intrasession repeatability of peripheral aberrations using COAS-HD VR aberrometer and also reported the distribution of higher order aberrations in a group of young emmetropes. There was no significant difference in the variance of total higher-order RMS between on- and off-axis measurements. There was a significant change in the horizontal coma, spherical aberration and higher-order RMS with off-axis angle along the horizontal visual field. We demonstrated that fast, repeatable and valid peripheral aberration measurements can be obtained with this instrument.

    This thesis contributes new results in this field of myopia, aberration and accommodation.

  • 14.
    Theagarayan, Baskar
    et al.
    Vision CRC, Australia ; Anglia Ruskin University, UK.
    Radhakrishnan, Hema
    Vision CRC, Australia ; , University of Manchester, UK.
    Allen, Peter M
    Vision CRC, Australia ; Anglia Ruskin University, UK.
    Calver, Richard I
    Vision CRC, Australia ; Anglia Ruskin University, UK.
    Rae, Sheila M
    Vision CRC, Australia ; Anglia Ruskin University, UK.
    O'Leary, Daniel J
    Vision CRC, Australia ; Anglia Ruskin University, UK.
    The effect of altering spherical aberration on the static accommodative response.2009In: Ophthalmic & physiological optics, ISSN 0275-5408, E-ISSN 1475-1313, Vol. 29, no 1, p. 65-71Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate the effect of altering the spherical aberration (SA) of the eye on the static accommodative response.

    METHODS: Participants were fitted with nominally afocal contact lenses with controlled amounts of SA of either -0.2, -0.1, 0.0, +0.1 or +0.2 microm for a 5-mm pupil. Measurements of SA and root mean square (RMS) total aberration for the eye plus lens for each participant were determined with a Complete Ophthalmic Analysis System aberrometer. Accommodation was stimulated either by placing targets at different dioptric distances from the eye, or by using a fixed distance target and placing negative-powered lenses in front of the eye. Accommodation responses were determined with a Shin-Nippon autorefractor.

    RESULTS: For both stimuli situations, the slope of the accommodation stimulus-response function was lowest for the lenses with +0.2 microm SA, and increased as the amount of SA was reduced. There was a significant negative correlation between SA and slope. Lag of accommodation at 33 cm correlated well with added SA, but did not correlate with total RMS error. There was no significant difference between the responses at 30 min after lens wear started and the responses after 1 h.

    CONCLUSIONS: Adding negative SA to the eye generally improves the slope of the accommodation stimulus-response curve and decreases lag of accommodation, and positive added SA depresses the slope of the stimulus-response curve and increases lag. The effect seems to be specific to SA, as there was no relationship between lag and RMS error. Altering SA may be a viable way of changing accommodative functions in clinical situations.

  • 15.
    Theagarayan, Baskar
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Sörman, Yelene
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Effect of Age on Amplitude of Accommodation in a Swedish Population2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 7Article in journal (Other academic)
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf